Avalanches in the Bean critical state: a characteristic of the random pinning potential

We report on two-dimensional simulations of the avalanche response of vortices in the Bean critical state of type-II superconductors. Two different kinds of repulsive-particle models are considered in order to make the findings generic. We use repulsive two-body potentials to represent the vortex-vortex interaction and an attractive two-body potential to represent the interaction between the static pinning wells and the vortices. We find that a collection of very short-ranged dense pinning centres leads to a broad distribution of response avalanches, whereas broader and less dense pinning centres produce a narrow distribution of responses.